Stunning! is an Achievement in Halo 3: ODST. It is obtained by disabling any Vehicle with an over-charged Plasma Pistol shot and killing the driver of the vehicle. It is worth 5 Gamerpoints. It is easily obtainable on the missions Kizingo Boulevard and Uplift Reserve. It is recommended to turn the difficulty down to Easy or Normal to earn this achievement. It can also be obtained if a Brute throws a Power Drain near a vehicle and you melee the driver.
It is represented by a gold 16-pointed star, with a green 16-pointed star within it, with a red circle, with a stop sign in the middle.